Erik Karlsson had an unbelievable season for the Ottawa Senators. Considering the contract he signed on Tuesday, he'll need to have several more.

The 22-year-old Norris Trophy finalist, coming off a 78-point 2011-12 season, signed a seven-year contract. The contract carries a $6.5 million cap hit, according to TSN.ca's Bob McKenzie, which makes Karlsson the sixth-best paid defenseman in the league.

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The players with larger cap hits are Brian Campbell ($7.143 million), Drew Doughty ($7 million), Zdeno Chara ($6.9 million), Jay Bouwmeester ($6.8 million) and Dan Boyle ($6.66 million). Campbell remains a valuable player, but his contract was a problem the day he signed it in 2008 with the Chicago Blackhawks. Since traded to the Florida Panthers, Campbell is signed through 2018. Doughty signed his deal at 21 and is better defensively than Karlsson, but struggled under the weight of the contract before rounding back into form during the Kings' Stanley Cup run. Chara remains a dominant two-way force for the Boston Bruins. Bouwmeester hasn't lived up to the deal with the Calgary Flames. Boyle's deal with the San Jose Sharks expires in 2014.

Those players run the gamut when it comes to returning the investment. They're all better defenders than Karlsson. And none have a 70-plus point season under their belt. The problem for Karlsson, though, is that while he generally played against the opponents' top competition, he also started more than 57 percent of his shifts in the offensive zone. That took significant defensive responsibility of his plate and helped contribute to both his point totals and solid puck possession numbers.

Given that, he needs to keep producing offense at a serious clip, and, as noted by Yahoo! Sports' Ryan Lambert, the only defenseman to top 70 points eight times in their careers are Ray Bourque and Paul Coffey, who were all-time great players during an era where it was significantly easier to score goals.

Just as importantly for the rest of the league, the contract will no doubt affect negotiations for unrestricted free agent Ryan Suter and RFA Shea Weber, defensive partners for the Nashville Predators who are, generally speaking, more complete players than Karlsson. Suter will likely see his $3.5 salary more than double, while Weber is coming off a one-year, record $7.5 million arbitration award.